Device and method for coating elongate objects

ABSTRACT

A device for coating an exterior of an elongate object includes a housing structure with an elongate chamber having first and second opposite ends. A port communicates with the first end for receiving the elongate object and an outlet is located at the second end. An air supply passage and a coating material supply passage communicate with the elongate chamber. Pressurized air and coating material are adapted to enter the elongate chamber through the air supply passage and the coating material supply passage, respectively, to form a mist in the elongate chamber moving toward the outlet while coating the exterior of the object. A method of coating an exterior surface of the elongate object with the coating material includes holding the elongate object lengthwise in the elongate chamber, mixing the pressurized air and the coating material to form a mist, and coating the exterior surface while directing the mist around the exterior surface and toward the outlet of the elongate chamber.

TECHNICAL FIELD

The present invention generally relates to the application of coatingsonto exterior surfaces of objects and, more specifically, the coating ofelongate objects such as needles.

BACKGROUND

Elongate objects are coated with material for various reasons. Forexample, hypodermic needles are often coated with lubricious orfriction-reducing materials, such as silicone based oils. This providesa low friction outer surface of the needle for purposes of easing theintroduction of the needle through the skin of a patient. Variousmethods and apparatus for applying the coating material to the needlehave been used in the past. These include dipping methods in which theneedles are dipped lengthwise into a bath containing silicone andsolvent. This method presents difficulties and challenges related tohandling the silicone and solvents, as well as the lengthy drying timesinvolved, and the ventilation needs due to the use of the solvents.

Other methods that have been employed in the past involve variousmanners of spraying the coating material onto the needle. Typically, thespraying device will discharge the coating material in a singledirection and the material will not flow around the entire exterior ofthe needle. For this reason, the needle and/or spray dispenser must berotated to evenly distribute the coating material on the entire exteriorsurface of the needle. Alternatively, multiple spraying devices may beused to coat all sides of the needle. Either case involves increasedcomplication and expense. The overspray or mist can also presentproblems in the environment around the equipment or require apparatusfor containing the overspray. Due to the viscosity of the fluid coatingmaterial, it can also be difficult to achieve the required thin, uniformlayer of coating material on the exterior surface of the needle.

It would therefore be desirable to provide a device and method foreasily coating an exterior of an elongate workpiece, such as a needle,while addressing various challenges presented by past devices andmethods.

SUMMARY

The present invention generally provides a device for coating anexterior of an elongate object. The device generally comprises a housingstructure including an elongate coating chamber having first and secondopposite ends. A port communicates with the first end for receiving theelongate object into the coating chamber and an outlet at the secondend. The coating chamber has at least first and second sections. Thefirst section is located closer to the outlet than the second sectionand the first section has a greater cross sectional area than the secondsection. The housing structure further includes an air supply passageand a coating material supply passage communicating with the elongatecoating chamber. The pressurized air and coating material are adapted toenter the elongate chamber through the air supply passage and thecoating material supply passage, respectively, to form a mist of the airand coating material. This mist is directed into the elongate chamberand generally toward the outlet while coating the exterior of theelongate object inserted into the elongate chamber through the port.

In a more specific embodiment, a mixing passage communicates with theair supply passage and the coating material supply passage. The mixingpassage further communicates with the elongate chamber. The pressurizedair and the coating material enter the mixing passage through the airsupply passage and the coating material supply passage, respectively,and the mist of the air and coating material begins to form in themixing passage before entering the elongate chamber.

A device constructed according to the exemplary embodiment furtherincludes various additional features. For example, a valve comprised ofa valve member and a valve seat selectively supplies the coatingmaterial to the elongate chamber. A ring shaped structure communicatesbetween the air supply passage and the mixing passage. The ring shapedstructure is configured to cause the pressurized air to enter the mixingpassage with a swirling motion about a discharge location of the coatingmaterial into the mixing passage. The ring shaped further includes acentral passage through which the coating material is directed into themixing passage and into the air moving with the swirling motion. Thedevice may further include a coating material injecting elementincluding a tube with an outlet. The tube extends through the centralpassage with the outlet of the tube positioned in the mixing passage.The ring shaped structure more specifically includes a ring shaped wallsurrounding an inner space and disposed around a central axis. Thecentral passage extends along the central axis. The ring shaped wallfurther includes a plurality of air directing passages communicatingbetween the air supply passage and the inner space so as to achieve theswirling motion around the central axis. The ring shaped structurefurther comprises a plurality of stand-off elements forming additionalair passages between the stand-off elements and providing communicationbetween the air supply passage and the mixing passage.

The elongate chamber is preferably configured with increasing diameterin a direction from the first end to the second end so that an increasein pressure is achieved in this direction within the chamber. The flowof the mist is generally along a central axis of the elongate chambercoaxial with the port at the first end. The mixing passage extendstransverse, and more preferably perpendicular, to the elongate chamber.

The elongate object further comprises a hollow needle having opposite,open ends, such as a hypodermic syringe needle. The device furthercomprises a needle holder including an interior air space and a needleholding element configured to secure a first end of the needle incommunication with the interior air space. The open second end of theneedle extends outwardly from the needle holder for insertion throughthe port and into the elongate chamber. The interior air space isadapted to be pressurized with air to force air through the needleduring a coating operation and prevent clogging of the open second endof the needle with the coating material.

In another aspect, a method is provided for coating an exterior surfaceof an elongate object with a coating material. The method generallyincludes holding the elongate object lengthwise in an elongate chamberhaving first and second opposite ends and an outlet at the second end. Amist is formed from a mixture of the air and the coating material andthe exterior surface is coated with the coating material while directingthe mist around the exterior surface of the elongate object and towardthe outlet of the elongate chamber.

The method practiced according to an illustrative example includesvarious additional aspects and steps. For example, the pressurized airand the coating material are first mixed within a mixing passageoriented transverse to the elongate chamber prior to directing the airand the coating material into the elongate chamber as a mist. The mixingpassage extends along an axis and the method further comprises swirlingthe air around the axis of the mixing passage at an air inlet to themixing passage, and directing the coating material into the mixingpassage along the central axis to mix with the swirling air. The methodfurther comprises directing the air into the mixing passage with aVenturi effect. Holding the elongate object further comprises directingthe object through a port at the first end of the elongate chamber andthe method further comprises directing additional air through the portand adjacent the object toward the outlet of the elongate chamber. Theelongate object further comprises a hollow needle with opposite, firstand second open ends, and the method further comprises directing airthrough the first open end of the needle and out of the second open endpositioned in the elongate chamber to prevent clogging of the first openend with the coating material. Directing the coating material into theelongate chamber further comprises actuating a valve to allowpressurized coating material to flow into the elongate chamber. Thecoating material may be a friction reducing material, such as a materialcontaining silicone.

Various additional features and advantages of the invention will becomemore apparent to those of ordinary skill in the art upon review of thefollowing detailed description of the illustrative embodiments taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a device constructed in accordance withan illustrative embodiment of the invention.

FIG. 2 is a cross sectional view generally taken along line 2-2 of FIG.1 and rotated 90° for purposes of easier explanation.

FIG. 2A is an enlarged view of the portion marked “2A” in FIG. 2.

FIG. 3 is a perspective view of the ring shaped structure used to directthe air flow within the device of FIG. 1.

FIG. 4 is a cross sectional view taken generally along line 4-4 of FIG.3.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

FIG. 1 illustrates a device 10 generally comprising a housing structure12 coupled with a conduit 14 suitable for containing control andelectrical supply wiring (not shown). An electrical coupler 16 isprovided and adapted to couple the device 10 to a controller 18 foroperating the device 10. A needle holder 20 is provided for introducinga needle to be coated, as further discussed below, into the housingstructure 12. More specifically, the needle holder 20 is adapted to abutan outside face 22 a of a first sub-housing 22 coupled to a secondsub-housing 24 of the housing structure 12 by fasteners 26.

Referring to FIGS. 2 and 2A, the first sub-housing 22 more specificallycomprises an elongate chamber 30 having first and second opposite ends32, 34. A port 35 at the first end 32 receives a needle 36 for coatingpurposes. The second end 34 defines an outlet. As shown in FIG. 1, thesecond end is fluidly coupled to an exhaust 39 including a filter. Theneedle holder 20 is mounted for movement in a manner (not shown) thatallows for repeatable introduction of successive needles 36 into thechamber 30 during a manufacturing operation. The needle holder 20includes an interior air space 20 a and a needle holding element 40. Theneedle holding element 40 grips the needle 36 with friction or in anyother suitable manner such that an open first end 36 a communicates withthe interior air space 20 a and an open second end 36 b is positionablewithin the elongate chamber 30. The needle 36 extends through the port35 preferably along the central axis of the port 35 and the elongatechamber 30. The needle 36 extends through a passage 42 in an insert 44within the first sub-housing 22 and the port 35 more specificallycomprises a conically shaped opening in the insert 44. As will be morespecifically described below, air is drawn in through the conicallyshaped port 35 into the passage 42 of the insert 44 and, finally, intothe elongate chamber 30. The elongate chamber 30 comprises cylindricalchamber portions 30 a, 30 b, 30 c of successively larger diameter forcreating an increasing pressure as pressurized air flows from the firstend 32 toward the second end 34 in the direction of the arrows 45. Atleast a portion of the elongate chamber 30 may be formed by the interiorof a tubular member 46 that is removably attached to the firstsub-housing 22 by respective threads 48, 50.

A mixing passage 52 in the first sub-housing 22 extends transverse and,more specifically, perpendicular to the elongate chamber 30. This mixingpassage 52 communicates directly with the smallest diameter chamberportion 30 a adjacent the insert 44 and needle port 35. As best shown inFIG. 2A, the first sub-housing 22 further includes a ring shapedstructure 54 for receiving pressurized air from an air supply passage56. The air supply passage 56 is coupled with a source 57 of pressurizedair. The pressure of the air is preferably in the range of one to fourbar. The ring shaped structure 54 further receives a coating materialinjecting element 58 including a tube 60 with a passage 60 a and anoutlet 60 b extending through a central passage 62 of the ring shapedstructure 54. The ring shaped structure 54 more specifically comprises aring sealed by respective O-rings 64, 66 within a recess 68 of the firstsub-housing 22 and against a surface 70 of the second sub-housing 24.

The coating material is provided from a suitable pressurized supply 72(FIG. 1). In the case of coating a hypodermic syringe needle, forexample, the coating materials are preferably silicone oils of variousviscosity ranging, for example, from the viscosity of water to 12,500mPas. Most applications currently contemplated will utilize a viscosityof 1000-3000 mPas. The coating material is directed through a supplypassage 74 (FIG. 2) and ultimately into the central passage 60 a of thetube 60 and is injected into the mixing passage 52 when a valve element76 positioned in the second sub-housing 24 is opened relative to a valveseat element 78 abutting an inlet end 58 a of the coating materialinjecting element 58. As will be described further in connection withFIGS. 3 and 4, the ring shaped structure 54 receives and directs the airin a swirling motion within an inner space 80 defined by a ring shapedor annular wall 82. The ring shaped wall 82 includes a plurality of airdirecting passages 84 communicating with the air supply passage 56through an annular air space 86 formed between the ring shaped wall 82and the wall 88 of the recess 68. The swirling air within an inner space80 is directed downwardly into a generally cone-shaped or convergingpassage 90 surrounding the tube 60 of the coating material injectingelement 58 and then into the mixing passage 52. Due to the constrictionformed by the converging passage 90, the air is directed into the mixingpassage with a Venturi effect in addition to the swirling motion. Theair then mixes with the injected coating material to form a mixture inthe form of a mist as the air and coating material enter the elongatechamber 30 through a connecting port 91.

More specifically referring to FIG. 2, the valve seat element 78 iscarried on a valve component 92 affixed to a main part of the secondsub-housing 24 by threaded fasteners 94 (only one shown). The valvecomponent 92 is mounted in sealing engagement with the main part of thesecond sub-housing 24 through the use of an O-ring 96. A passage 98 ofthe valve component 92 communicates with a passage 100 in the secondsub-housing 24 containing the reciprocating valve element or valve stem76. The passage 100 communicates with the coating material supplypassage 74 and, ultimately, with the coating material supply 72 (FIG.1). The valve stem 76 includes an additional dynamic seal 102 engagedwith the internal wall defining the passage 100 to prevent the coatingmaterial from leaking into the interior space 104 of the secondsub-housing 24 which contains valve stem actuating components, includingan actuating arm 106. The valve stem 76 and actuating arm 106 may beactuated in any suitable manner such as by using a conventionalpiezo-electric actuator (not shown).

Referring to FIG. 2A in combination with FIGS. 3 and 4, the ring shapedstructure 54 includes the ring shaped wall 82 surrounding the innerspace 80 and the wall 82 is spaced around a central axis 108. Thecentral passage 62 extends in a coaxial fashion around the central axis108 and the ring shaped wall 82 further includes the plurality of airdirecting passages 84 communicating with the annular space 86 (FIG. 2A)which, in turn, communicates with the pressurized air supply passage 56.The air directing passages 84 are formed in a generally tangentialmanner relative to the cylindrical shape of the inner space 80 as bestillustrated in FIG. 4 such that air entering the inner space 80 travelswith a swirling motion as shown by the arrows 109. A plurality ofstand-off elements 110 extends from a lower end of the ring shapedstructure 54 and provide for additional air passages or paths 112 (FIG.2A) between the stand-off elements 110 and between lower surfaces 114 ofthe ring shaped structure 54 and the bottom wall 116 (FIG. 2A) of therecess 68, as shown in FIG. 2A. Therefore, air will enter an annularspace 86 from the air supply passage 56 and, from the annular space 86,pass through the air directing passages 84 into the inner space 80, andalso pass between the stand-off elements 110 through passages 112. Theair passing through the air directing passages 84 will cause a swirlingair motion within the inner space 80 and this air will be directeddownwardly to combine with the air passing between the stand-offelements 110 and then enter the inlet 90 of the air mixing passage 52with a swirling motion and Venturi effect, i.e., reduced pressure andincreased velocity. This mixing action will begin to form a mist withthe coating material being injected through the outlet 60 b of the tube60 along the central axis 108 of the ring shaped structure 54 and thecoaxial central axis of the mixing passage 52. The flow within theelongate chamber 30 will draw additional air into the port 35 as shownby arrows 119 and through the passage 42 of the insert 44 (see FIGS. 2and 2A) to prevent any coating material from traveling in the oppositedirection through the port 35. At the same time, pressurized air in theinterior air space 20 a will travel as illustrated by the arrow 120 inFIG. 2A through the open first end 36 a of the needle 36 and out of theopen second end 36 b of the needle 36 to prevent the second end 36 b ofthe needle 36 from being clogged by coating material in the mist. Thecontroller 18 (FIG. 1) will operate the actuating arm 106 to open andclose the valve stem 76, and operate the pressurized air in an on/offfashion as necessary to successively coat multiple needles 36 in serialfashion as they are introduced one-by-one into the elongate chamber 30by the same or different needle holders 20.

The first sub-housing 22 may be removed from the second sub-housing 24for repair and replacement purposes. More specifically, componentscontained in the first sub-housing 22 may become contaminated due to theenvironmental air that is being suctioned into the passages of thosecomponents and mixed with the coating material. On the other hand, thecomponents and passages associated with the second sub-housing 24 needmuch less service during regular use. Thus, the second sub-housing 24and its associated components may remain mounted while the firstsub-housing 22 and its attached components are removed from the secondsub-housing by removing fasteners 26. The components 44, 46, 54, 58associated with the first sub-housing 22 may be easily disassembled forcleaning purposes. In addition, the modular nature of the firstsub-housing 22 allows different application requirements to beaccommodated, such as size changes to accommodate different elongateobjects, and adjustments to the type and/or viscosity of coatingmaterial. In addition, the injecting element 58 may be replaced toaccommodate a coating material having a different viscosity. Finally,the insert 44 receiving the elongate object 36 may be modified forparticular applications, such as coating operations of syringe tips withvarious configurations.

While the present invention has been illustrated by a description ofvarious preferred embodiments and while these embodiments have beendescribed in some detail, it is not the intention of the Applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. The various features of the invention may beused alone or in any combination depending on the needs and preferencesof the user. This has been a description of the present invention, alongwith the preferred methods of practicing the present invention ascurrently known. However, the invention itself should only be defined bythe appended claims. What is claimed is:

1. A device for coating an exterior of an elongate object, comprising: ahousing structure including an elongate coating chamber having first andsecond opposite ends, a port communicating with said first end forreceiving the elongate object into the coating chamber and an outlet atsaid second end, said coating chamber having at least first and secondsections, said first section located closer to said outlet than saidsecond section and said first section having a greater cross sectionalarea than said second section, the housing structure further includingan air supply passage and a coating material supply passagecommunicating with said elongate coating chamber; wherein pressurizedair and coating material are adapted to enter said elongate chamberthrough said air supply passage and said coating material supplypassage, respectively, to form a mist of the air and coating materialthat is directed into said elongate chamber and generally toward saidoutlet while coating the exterior of the elongate object inserted intosaid elongate chamber through said port.
 2. The device of claim 1,further comprising: a mixing passage communicating with said air supplypassage and said coating material supply passage, said mixing passagefurther communicating with said elongate chamber, wherein pressurizedair and coating material are adapted to enter said mixing passagethrough said air supply passage and said coating material supplypassage, respectively, to form the mist of the air and coating materialthat is directed into said elongate chamber and generally toward saidoutlet while coating the exterior of the object inserted into saidelongate chamber through said port.
 3. The device of claim 2, whereinsaid elongate chamber includes a central axis coaxial with said port,and said mixing passage extends transverse to said elongate chamber. 4.The device of claim 1, further comprising: a ring shaped structurecommunicating between said air supply passage and said elongate chamber,said ring shaped structure configured to cause a swirling motion of thepressurized air, said ring shaped structure further including a centralpassage through which the coating material is adapted to be directedinto the air moving with the swirling motion to thereby form the mist.5. The device of claim 4, further comprising a coating materialinjecting element including a tube with an outlet, said tube extendingthrough said central passage.
 6. The device of claim 5, wherein saidring shaped structure further comprises a ring shaped wall surroundingan inner space and disposed around a central axis, and wherein saidcentral passage extends along the central axis, said ring shaped wallfurther including a plurality of air directing passages communicatingbetween said air supply passage and said inner space and directing thepressurized air into said inner space in the swirling motion around saidcentral axis.
 7. The device of claim 4, wherein said ring shapedstructure further comprises a plurality of stand-off elements formingadditional air passages communicating between said air supply passageand said elongate chamber.
 8. The device of claim 1, further comprising:a valve member and a valve seat mounted in said coating material supplypassage, said valve member movable with respect to said valve seat toselectively supply the coating material to the elongate chamber.
 9. Thedevice of claim 8, wherein said housing structure further comprises afirst sub-housing and a second sub-housing, said first sub-housing beingremovably coupled to said second sub-housing and containing saidelongate coating chamber, and said second sub-housing containing saidvalve member and said valve seat.
 10. The device of claim 1, wherein theelongate object further comprises a hollow needle, and furthercomprising: a needle holder including an interior air space and a needleholding element configured to secure a first end of the needle incommunication with the interior air space while an open second end ofthe needle extends outwardly from said needle holder for insertionthrough said port and into said elongate chamber, wherein said interiorair space is adapted to be pressurized with air to force air through theneedle and prevent clogging of the open second end of the needle withthe coating material.
 11. The device of claim 1, wherein said port isconfigured to allow additional air to be drawn into said elongatechamber as the mist is coating the exterior of the elongate object. 12.A device for coating an exterior of an elongate object, comprising: ahousing structure including an elongate coating chamber having first andsecond opposite ends, said elongate coating chamber including a portcommunicating with said first end for receiving the elongate object andan outlet at said second end, an air supply passage, a coating materialsupply passage, and a mixing passage communicating with said air supplypassage and said coating material supply passage, said mixing passagefurther communicating with said elongate coating chamber; and a ringshaped structure communicating between said air supply passage and saidmixing passage, said ring shaped structure configured to cause thepressurized air to enter said mixing passage with a swirling motion,said ring shaped structure further including a central passage throughwhich the coating material is directed into said mixing passage and intothe air moving with the swirling motion; wherein the pressurized air andcoating material in said mixing passage form a mist in said elongatechamber moving toward said outlet while coating the exterior of anobject inserted into said elongate chamber through said port
 13. Thedevice of claim 12, wherein said ring shaped structure further comprisesa ring shaped wall surrounding an inner space and disposed around acentral axis, and wherein said central passage extends along the centralaxis, said ring shaped wall further including a plurality of airdirecting passages communicating between said air supply passage andsaid inner space and directing the pressurized air into said inner spacein the swirling motion around the central axis.
 14. The device of claim13, wherein said ring shaped wall further comprises a plurality ofstand-off elements forming additional air passages communicating betweensaid air supply passage and said mixing passage.
 15. The device of claim12, further comprising a coating material injecting element including atube with an outlet, said tube extending through said central passagewith said outlet positioned in said mixing passage.
 16. The device ofclaim 12, further comprising: a valve member and a valve seat mounted insaid coating material supply passage, said valve member movable withrespect to said valve seat to selectively supply the coating material tothe elongate chamber.
 17. The device of claim 12, wherein said port isconfigured to allow additional air to be drawn into said elongatechamber as the mist is coating the exterior of the elongate object. 18.The device of claim 12, wherein said elongate chamber includes a centralaxis coaxial with said port, and said mixing passage extends transverseto said elongate chamber.
 19. The device of claim 12, wherein theelongate object further comprises a hollow needle, and furthercomprising: a needle holder including an interior air space and a needleholding element configured to secure a first end of the needle incommunication with the interior air space while an open second end ofthe needle extends outwardly from said needle holder for insertionthrough said port and into said elongate chamber, wherein said interiorair space is adapted to be pressurized with air to force air through theneedle and prevent clogging of the open second end of the needle withthe coating material.
 20. The device of claim 12, wherein said ringshaped structure includes an air passage forming a constriction intosaid mixing passage thereby causing a Venturi effect of the air enteringsaid mixing passage.
 21. The device of claim 12, further comprising: avalve member and a valve seat mounted in said coating material supplypassage, said valve member movable with respect to said valve seat toselectively supply the coating material to the elongate chamber.
 22. Thedevice of claim 21, wherein said housing structure further comprises afirst sub-housing and a second sub-housing, said first sub-housing beingremovably coupled to said second sub-housing and containing said mixingpassage, said ring shaped structure and said elongate coating chamber,and said second sub-housing containing said valve member and said valveseat.
 23. The device of claim 12, wherein said port is configured toallow additional air to be drawn into said elongate chamber as the mistis coating the exterior of the elongate object.
 24. A method of coatingan exterior surface of an elongate object with a coating material,comprising: holding the elongate object lengthwise in an elongatechamber having first and second opposite ends and an outlet at thesecond end, mixing pressurized air and the coating material to form amist; and coating the exterior surface with the coating material whiledirecting the mist around the exterior surface and toward the outlet ofthe elongate chamber.
 25. The method of claim 24, further comprising:mixing the pressurized air and the coating material in a mixing passageoriented transverse to the elongate chamber prior to directing the airand the coating material into the elongate chamber.
 26. The method ofclaim 25, wherein the mixing passage extends along an axis, and themethod further comprises: swirling the air around the axis at an airinlet to the mixing passage; and directing the coating material into themixing passage along the central axis to mix with the swirling air. 27.The method of claim 26, further comprising: directing the air into themixing passage with a Venturi effect.
 28. The method of claim 24,wherein holding the elongate object further comprises directing theobject through a port communicating with the first end of the elongatechamber, and the method further comprises: directing additional airthrough the port and adjacent the object toward the outlet of theelongate chamber.
 29. The method of claim 24, wherein the elongateobject further comprises a hollow needle with opposite, first and secondopen ends, and the method further comprises: locating the second openend in the elongate chamber; and directing air through the first openend of the needle and out of the second open end to prevent clogging ofthe second open end with the coating material.
 30. The method of claim24, wherein directing the coating material further comprises: actuatinga valve to allow pressurized coating material to flow into the elongatechamber.
 31. The method of claim 24, wherein the coating materialcomprises a friction reducing material.
 32. The method of claim 24,wherein directing the mist toward the outlet further comprises:directing the mist through sections of the chamber having increasingdiameter.